DC2NET Links

Hi there,
This is my first post, so please be gentle!
I am looking at giving my website some free SEO tools, and one of them would be a google sitemap generator.
I cant help but notice that 99% of the free ones online have a maximum 500 page limit.
Why is that?
If i were to have a , for example, 1000 page limit program written for me and installed at my site, would i be in danger of killing my host-bandwith?
cheers in advance
dave